The overall objectives of this project are to attempt to identify the individual differences in the behavioral repertoire of infants and to determine how these differences interact with environmental experiences to result in particular developmental outcomes in normal and risk populations. In pursuit of these goals we have developed an observational system to make a comprehensive record of mother-infant environmental interactions which we use in combination with infant assessment to look for interactive functions. Our goals for the current year were to collect data on middle class and premature samples, to complete analyses of the 1300 NBAS-K exams on normal infants, to further develop the NBAS-K for use with premature and high-risk infants.